We conducted a systematic study on pressure-dependent electrical, vibrational and structural properties of titanium ditelluride up to 43.4 GPa. The room-temperature resistivity shows a series of anomaly changes at around 6, 13 and 22 GPa. Low-temperature resistance measurement was also employed to better understand the electronic structure and we observed the superconductivity at about 6 GPa successfully. Raman spectroscopy and X-ray diffraction (XRD) experiment show a topological phase transition at about 6 GPa followed by a structure phase transition at about 13 GPa. The P3m1 to C2/m phase transition begins from about 13 GPa and completes at about 22 GPa. The XRD data correlate well with our electronic transport measurement result, which shows a pressure-induced structure evolution and electronic structure modification. Therefore titanium ditelluride may provide us with a new perspective to understand the high pressure behaviors in transition metal dichalcogenides.

The systematic test and analysis of the spectral characteristics and color mechanism of the synthetic jadeite are carried out by using electron probe, X-ray powder diffraction, Fourier transform infrared spectroscopy, laser Raman spectra and UV-VIS absorption spectra and photoluminescence spectra.The research results show that the appearance, mineral composition, Raman spectra, and photoluminescence spectra of the synthetic jadeite are almost the same as natural jade.However, there are obvious differences between FTIR, UV-VIS and chemical components.The specific performance is as follows:the low content of Fe leads to the loss of 437 nm absorption band in the visible range; in addition, the differences of content of trace elements and formation environment lead to large differences of infrared absorption band caused by stretching vibration of ν(M/Cr-O) and ν_as(M-OH).

Transient resistance is one of the most important parameters in the process of electric explosion.The accurate description of the nonlinear time-varying characteristics of the exploding wire resistance is the key to the simulation of electric explosion, which determines the simulation precision.In order to solve the problem of poor precision associated with traditional simulation model, this paper presents a piecewise calculation method based on current density to correct the relationship between traditional resistivity and specific action, and establishes a piecewise calculation electric explosion simulation model based on the current density.The results show that, under the condition of large pulse current, the precision of the model is higher than that of the traditional simulation model, which can be used to study the electric explosion process with high accuracy.

This paper introduces a novel ultra-high pressure device, double-beveled multilayer stagger-split die.This device consists of a double-beveled sector block cylinder, a discrete prestressed ring and a hoop ring.We explored the force situation of the double-beveled multilayer stagger-split die, and the results were compared with those of the belt type die.The results show that the von Mises stress and maximum shear stress of the double-beveled multilayer stagger-split die is 46.8% and 50.9% lower than that of the belt type die.The experimental results show that the pressure of the double-beveled multilayer stagger-split die is about 78% higher than that of the belt type die.At last, the double-beveled multilayer stagger-split die is easy to manufacture and assemble, and can achieve large cavity mold manufacturing.

In this study, the capsular carbon nanomaterials with large specific surface area are synthesized using gas phase detonation method doped with acetylene gas, oxygen and pentacarbonyl iron.The pre-experimental of the reaction for the thermal decomposition reaction of carbonyldiiron showed that the iron octacarbonyl diketones were thermally decomposed according to nine carbonyldiiron decomposed into iron pentacarbonyl and tricarbonyl dodecylcarbonyl between 60 and 140℃.The morphology and components of the synthesized nanoparticles were characterized through X-ray diffraction studies, transmission electron microscopy and physical adsorption instrument analyses.Results showed that the graphite peaks can be clearly observed in XRD pattern and the product is mainly with a structure that capsular amorphous carbon with thin layer which has graphitization tendency.The experimental product has a specific surface area of 253.857 m²/g, a pore volume of 0.940 cm³/g and an average pore size of 2.731 nm, type of the hysteresis loop of the adsorption & desorption curve is H3.The pore structure is mainly formed by the accumulation of granules and has a large specific surface area and a strong adsorption capacity.The article confirms that iron is also used as a catalyst.Acetylene cannot be used to synthesize carbon nanotubes without adding an inert gas as a buffering agent due to its high detonation velocity.

Based on the molecular structural mechanics and multi-scale method, the finite element model of graphene reinforced epoxy resin composite with different number of vacancy defects and Stone-Wales (S-W) defects was constructed by using the finite element commercial software ABAQUS.The effects of graphene defects on the elastic modulus and interfacial stress transfer of composites with different volume fractions of graphene were investigated.The numerical simulation results show that the elastic modulus of the perfect graphene and the defective graphene reinforced epoxy resin composite increases linearly with the increase of the volume fraction of graphene.Secondly, the comparison between the number of defects and the type of defects shows that the vacancy defect can obviously reduce the modulus of elasticity of the composite, and the change is more obvious with the increase of the number of defects.However, the S-W defect increases the Young's modulus of the composites to a certain extent, but the shear modulus decreases.In addition, the stress transfer from the interface layer to some extent reflects the effect of defects on the composites.

The fatigue analysis for a whole pipeline system is rather rare to date, while in this paper, we accomplished an integrated computational fatigue analysis of the pipeline system based on model constructing and fluid-solid coupling by using Workbench and nCode DesignLife method.And the high pressure industrial water pipeline is studied under normal interior flow velocity and high working pressure conditions respectively.The fatigue response of the system and individual part is affected by various inlet velocities and random excitation forces.The results indicate that the interior flow velocity of each part in industrial high-pressure pipeline should be monitored for the system health.The fatigue failures generally occur on the connecting parts, especially at the interior intersecting line segments.Piping system can extend the fatigue life of flanged pipe at extreme states.This work provides a significant reference for the design of the high pressure industrial piping system in preventing the fatigue failure.

Based on the similar model test, the damage evolution and dynamic response law of anchored caverns with a crack under top explosion was studied by numerical analysis, and the influence of crack angle and length on the damage distribution and crown displacement of the anchor caverns was discussed.With the propagation of the explosion stress waves, tensile damage is formed on the surface of the fracture, and a winged crack extends at the tip of the fracture.Subsequently, a large tensile damage zone was formed successively at the vault free surface near the anchoring cavern, at the boundary of the anchoring zone, and in the middle of the floor.As the crack angle increases from 0° to 90°, the area of the largest damage zone at the boundary of the anchorage zone and the anchorage zone first decreases and then increases, and the area at the crack inclination angle of 45° is the smallest.When the cracks have the same length, the peak displacement of the crown increases first and then decreases with the increase of the crack dip angle.When the fracture angle is the same, the longer the crack length is, the more obvious the obstruction of the stress wave is, and the damage of the cavern with the facture 30 cm in length and 45° in inclination angle under top explosion is minimal.

Many factors can cause natural gas explosions, and it will lead to serious structural damages and human injures.This study is focused on the leakage of natural gas from underground pipe gallery.A case study has been made in a project of the circular island road in Pingtan comprehensive test.An underground explosion was modeled by use of the fluid-solid coupling and multi-material ALE algorithm in finite element software LS-DYNA.On this basis, the influence of explosion shock wave on the surrounding structure was discussed.Numerical results show that, during the whole process of the explosion, the overpressure transferred from explosion source center to the wave front, leading to the lower pressure in the explosion source compared to the wave front and the formation of a negative pressure zone near the explosion source.The overpressure value of point which is on the internal wall closest to the explosion source in the gas cabin is larger than that of other points.The maximum overpressure is 18.65 MPa at t=7.8 ms.At t=10 ms, the displacement and velocity reach their own maximum values of 10.47 mm and 3.303 m/s, respectively.Explosion in the gas cabin, interior wall experiences positive and negative pressure oscillation with long duration, the vibration phenomenon is most obvious and the structure is easy to be failure.

In order to study the meeting location of fragments and shock waves after fragmentation warhead explosions, ANSYS/LS-DYNA was first used to numerically calculate the explosion process of the fragmented warhead, and then the location where fragments meet shock wave was experimentally determined, validating the numerical method.On the basis of above results, the influence of k, m, Q_V and Q_T on the meeting location was analyzed.The results show that the meeting location decreases with the increase of k, m, Q_V and Q_T.More precisely, the k increases by 31%, the distance between the meeting position and the explosion center decreases by 11.5%, the m is doubled, and the distance between the meeting position and the explosion center is reduced by 2.4%.

According to the instantaneous detonation, under the minimal charge ratio (C/M) condition, we study that small-mass explosives drive mass load to move.The load driving speed is deduced under the charge conditions subjected to weak constraint and strong constraint.Under the weak constraint charge condition, considering the radial scattering of the charge shells, the two-dimensional calculation model of the load motion of the explosives is obtained base on Gurney equations.Under the strong constraint condition, according to the entropy expansion of the detonation product, the calculation model of the mass loading driven speed is obtained.The motion test of the mass driven by the detonation is carried out under two kinds of constraints.Under the weak constraint condition, the load driving speed increases with the decrease of the length-diameter ratio of charge.Under the strong constraint condition, the load driving speed increases with the increase of the charge weight, and with the increase of the diameter ratio of the charge cavity and the moving cavity.

When the bubble develops in shallow water between the free surface and the bottom, extremely complex phenomena of the free surface will be caused.The bubble motion characteristics are different from that in the free field.To explore its patterns, spark induced bubble experiments are carried out and high-speed video-photography is employed to study the interaction between bubbles and combined boundaries.The influence of distance parameter on dome type and bubble motion has been summarized.The influence of distance parameter on jet loading is analyzed by numerical simulation using OpenFOAM.The results show that the free surface distance parameter has a greater influence on the type of dome than that of the wall distance parameter.The jet velocity decreases with the increase of the free surface distance.The jet velocity first decreases and then increases with the increase of the wall surface distance.The pressure on the wall decreases with the distance increasing while the jet impact area increases with the distance increasing.

In order to investigate the armor penetration aftereffect of depleted uranium alloys liner, a series of aftereffect experiments are conducted using depleted uranium-Ni alloys liner.The results show that, a high-speed and high-temperature flaming grain bundle is formed after depleted uranium alloys jet penetrating the steel stick, and the fire ball has great incendiary power.Pressure of the inside space barely change after depleted uranium alloys jet penetrating the closed armor target, but the temperature of the location towards shaped charge jet has increased 15℃ in 0.2 s, and the whole temperature of the armor target has increased 2.5℃ eventually.

There is accumulation in the middle of the jets formed by the single cone liner in the annular shaped charge structure, and the length of the jet is limited before the fracture.The jet of the double cone liner takes both the high head speed formed by upper small angle cone liner and increscent effective mass of the jet formed by the lower cone liner.Therefore, the jet is more slender with high head speed and it is not easy to break.Based on the annular cutting shaped charge warhead, the influence of the upper cone size, the proportion of the upper cone cover, the mask height and the wall thickness of the liner on the penetration capability of jet is considered.It is concluded that the upper cone angle has the greatest influence on the jet molding.By comparison, when the top cone cover is 34°, the proportion of top cone is 40%, the height of the liner is 70 mm and the wall thickness of the liner is 5 mm, the jet head can fly steadily in the air with a high speed.Compared with the single cone liner structure, the jet formed by the double cone liner is long and slender, and has long flight time in the air, its penetration capability is greater than that of the single cone jet.

To improve the performance of linear shaped charge jet, this study applies the truncated and auxiliary liner structure to the linear shaped charge.The three-dimensional finite element analysis software (LS-DYNA) was used to simulate the linear shaped charge jet formed with copper as the main liner and Al, Cu and W as auxiliary liner.At the same time, comparison between the formed linear shaped charge jet and the traditional jet is performed, indicating that the jet formed by the truncated and auxiliary liner structure has better performance.With the increase of the density and hardness of the auxiliary liner material, the jet's ductility, speed and effective mass are improved and all of them are superior to the traditional wedge cover structure.Compared with the conventional wedge cover structure, the speed and the effective length of the jet utilizing W as the auxiliary material increase about 25.9% and 145%, respectively.

To enhance the protective capabilities of reactive armor, five different sizes of reactive armor with multi sandwich structure were designed and obtained.The first size of reactive armor added a layer of steel to the middle of the traditional reactive armor, and the second to fifth sizes of reactive armor were designed based on the first one, but the total thickness of the reactive armor is the same as the traditional reactive armor.ANSYS-LSDYNA software was used for numerical simulation.Comparisons between the new reactive armor and the traditional reactive armor were performed, focusing on the moment of jet break, the moment when the jet just collides with the target, the moment when the jet loses interference, and the penetration result of the target.In order to highlight the strength of the interference capacity of the new structure reactive armor in a more direct manner, the six reactive armors were compared in terms of the penetration data with two-layer reactive armor.The simulation results show that the A-type reactive armor of head jet has the longest deflection distance; the interference time of the new structure reactive armor to the jet is longer than that of the traditional reactive armor, and the interference time of the E-type reactive armor to the jet is the longest; A-type reactive armor has the best protection performance; when the reactive armor has the same thickness with the traditional reactive armor, the D-type reactive armor has the best protection effect.The A-type, D-type, and F-type reactive armors were selected for verification experiments.The experimental results show that the numerical simulation results are reliable.

Based on the existing double-layer flat-charge explosive reactive armor (ERA), we designed 4 different structures of double-layered wedge-charge ERA, and employed the LSDYNA-3D software to evaluate their ability of interfering with the jet.We analyzed the motion state of flying-plates, the velocity and deflection of the jet head, the slug fracture, the depth of penetration, and the jet distribution in the target to select the optimal solution.The comparison shows that Scheme 3 has the fastest jet velocity reduction rate with the smallest and evenly distributed penetration depth.It can be seen that Scheme 3 has the best protection performance, followed by Scheme 4, Scheme 1 and Scheme 2 in sequence.In Scheme 3 and Scheme 4, a composite flying-plate layer similar to the explosion welding principle has been observed.Through the simulation study of the double-layer wedge-charge ERA, it is found that the reasonable use of the wedge-shaped charge can make the jet cutting more uniformly and enhance the protective performance of tanks, which provides a theoretical basis for future research on the charge structure.

In order to study the influence of impact points in the midline of a double-wedge charge reaction armor on jet interference, their abilities to interference jet are evaluated by the simulation software LSDYNA-3D.The important results such as the movement state of the flyer during the penetration process, the fracture condition of the slug, the instantaneous velocity of the target after exposure, the penetration depth of the target, and the opening pit were analyzed.The simulation results were compared with the experimental results as well.It was found that the impact of the boundary effect is significant when the target is in the top of the armored midline of the double-wedge charge.The impact of the double-wedge charge on the jet is less significant, the slug cannot break before reaching the target plate, leading to the breakdown of the target plate.For the impact point of 160 mm, the jet penetrates into the armor of the double wedge charge and the slug rupture time is earliest compared to the other impact points.Moreover, the slug is cut into multiple segments with significant displacement and the lowest instantaneous speed when colliding with the target plate, leading to the minimum penetration depth.Therefore the anti-penetration performance is superior to the traditional double-layer flat charge.The maximum error between the simulation results and the experimental measurement is less than 10% and therefore they agree with each other.

In order to investigate the dynamic response of plates with preformed holes under internal blast load in the cabin model, the deformations of the plates with offset preformed holes and the plates with uniform preformed holes in the cabin model were experimentally investigated.The results are also compared with that of the plates with non-preformed holes.The numerical calculation of the internal blast load was carried out by using established simulation model of cabin.The distribution of internal blast shock waves at typical gauge points was analyzed and the deformation rules of plates with preformed holes were studied as well.The research results indicate that the effect of gain of deflection deformation obtained from decreasing local strength due to the preformed holes is greater than that of the blast venting.The shock wave exhibits the reflection and convergence phenomena inside the cabin model and a quasi-static feature during the late stage of milliseconds.The simulation results are consistent with the experimental ones.At the same time, there are differences between the thinning rates in different areas of the plates with preformed holes.The current research can provide reference for the analysis of the mechanism of coupling damage between shock wave and fragments in the cabin.

In this study, the influence of bulkhead perforation structure caused by half armor piercing warhead on the cabin burst effect is studied.LS-DYNA finite element software is used to simulate the internal explosion test of the small ship cabin with the help of reasonable material constitutive relation, equation of state, and the failure criterion at the connection between the material and the structure.The effectiveness of the model is verified by comparing the calculated peak value of shock wave in cabin with corresponding experimental data.By establishing different sizes of bullet holes, the influence of bullet hole size on cabin explosion effect is analyzed.It is concluded that peak value of shock wave overpressure decreases and the peak time of shock wave overpressure is delayed.When the diameter of the bullet hole is less than 1/10 of the bulkhead, the impact of the missile on the chamber explosion effect is negligible.

In the process of electromagnetic rail propulsion, the contact area temperature between armature and rails is one of the important indicators to measure contact state, which can characterize the degree of rail damage to some extent and affect the launch efficiency.Corresponding simulation analysis and measurement experiment of temperature characteristics are carried out.Based on the theory of electrical contact, the model is developed to analyze heat sources of the contact area and the influences on surface temperature.The change of temperature under different heat sources is obtained by simulation.Taking the electromagnetic rail propulsion device as the test platform, the temperature measurement experiment is carried out by using the measurement system based on infrared radiation.The temperatures of several typical positions under typical loading current are obtained.The results show that the measured temperature is consistent with the simulation results in amplitude and trend.Further analysis of the rail damage test can reflect that the increase of contact surface temperature accelerates the ablation of rail surface.

The aim of this work was to evaluate the effect of high pressure processing (HPP) with different holding time on the quality of pomfret (Pampus argenteus) during cold storage. Different processing times (10, 20 and 30 min) at 200 MPa were applied and HPP treated pomfret were compared with untreated samples. Microbiological parameter (total viable count (TVC)), physicochemical (pH and total volatile base nitrogen (TVB-N), color difference, water holding capacity (WHC), texture profile analysis (TPA)) and sensory evaluation were performed respectively after the application of high pressure treatment on pomfret at the interval of 2 d (2 days).The significant difference (P < 0.05) regarding the results have been observed between HPP and CK group after 2 d storage on the values of TVC, pH, TVB-N, △E(Total color difference), WHC, TPA and sensory score. The controlled groups were the first to present signs of degradation reaching rejection[JP]threshold values for all evaluated parameters. The shelf life of CK group was only 4-5 d. HPP treatment has shown to be effective in inhibiting microorganism growth, protein degradation and the drip loss in samples and the texture characteristic of samples can be better maintained. The results of correlation analysis of different groups suggested that the correlation between △E, pH, TVB-N and TVC were significant. The shelf-life of treated pomfret samples can be extended from 4 d to 8-12 d and the optimal condition of fresh keeping effects was 200 MPa and 30 min.